Hydraulic press



HYDRAULIC PRE vi JNVENTOR. VVALTE F1 F'Ewms.

A TTORNEY.

ug. 34,1934. W, FERRls Y 1,970,134

' HYDRAULIC PRESS Filed July 29, 1932 5 sheets-sheet 2 INVENToR. WALTERFEHRIS.

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ATTORNEY.

RE SE RVO/ R Aug.14,1934. WQRRB 1,970,134

HYDRAULIC .PRES S Filed July 29, 1952 3 sheets-sheet s 85 38. d [Ol 79a9 @Oraaob 6; 34 a l .a a S/.o2 57 l g- E* d 15/ il-: 76.

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Patented Aug. 14, 1934 HYDRAULIC PRESS Walter Ferris, Milwaukee, Wis.,assigner to The Gilgear Company, Milwaukee, yWis., a corporation ofWisconsin Application July 29, 1932, Serial No. 625,765

Cla (Cl. 113-45) This invention relates to draw presses.

The draw press to which the invention applies in particular is providedwith a pair of dies for forming articlesfroxn sheets or blanks, a blank.

d folder for pressing the margin of the blank against one of the dies toclamp it therebetween during the drawing operation, and means for movingone of the dies toward and from thek be applied to the blank atdifferent points around a the margin thereof.

29 .Another object is to provide a press with a blank holder which maybe readily adiusted to apply di'erent pressures at different points uponthe margin of a blank.

Another object is to provide a press of this 2b character which is fluidoperated.

Another object is to provide means whereby a plurality of cylindersmaybe supplied with pressure fluid from a single source and pressure bemaintained in one cylinder while fluid is being 2li delivered to anothercylinder.

, Another ,object is to provide a press with a fluid operated blankholder in which sylphons are employed for transmitting pressure toselected points upon the margin of the blank.

Another object is to provide. a press of this character which issusceptible of close adjustment and control.

According to the invention in a general aspect, the press is providedwith a plurality of cylinders which are supplied with pressure fluidfrom a single source, and means are provided for regulating the pressurein one cylinder without affecting the pressure in another cylinder.

-iccording to the invention in another aspect,

the press is provided with a ram cylinder rand a blank holder cylinder,pressure iiuid is delivered freely from a suitable source to the ramcylinder to operate a ram arranged therein, and a choke is connectedbetween the blank holder cylinder and said source to enable the' same tomaintain pressure in the blank holder cylinder while delivering fluid tothe ram cylinder.

According to the invention in another aspect, the blank holder of thepress is provided with @5 huid actuated sylphons which may be moved fromplace to place to exert pressure upon the blank at different pointsaround the margin thereof.

The invention is illustrated by the press shown in the accompanyingdrawings in which the views are as follows:

Fig. 1 is a central Vertical section through the press, the view beingsomewhat diagrammatic in character and the piping-and certain otherparts being omitted or broken away.

Fig. 2 is a plan view on the line 2-2 of Fig. 1.

Fig. 3 is a central vertical section through one of the sylphons shownin Fig. l.

Fig. 4 is a diagram of one part of the hydraulic circuit and shows thevalves in central longitudinal section with the plungers thereof in thepositions occupied when the press is idle.

Fig. 5 is a diagram of another part of the hydraulic circuit.

Figs. 6, 7, 8, 9 and 10 are views showing the plungers of the severalvalves in different positions from those shown in Fig. 4.

The press shown in Figs. 1 and 2 is provided with a base l, which isarranged upon a suitable foundation 2 and rigidly secured in astationary position thereon by anchor bolts 3, and with a crosshead 4which is supported above the base 1 and fixed in a stationary positionrelatively thereto byfour columns or strain rods 5.

The crosshead l carries upon the under side thereof a bolster 6 to theunder side of which a stationary female die "7 is attached and providedat its center with a recess 8 to receive the head 9 of a knockoutplunger 10 which extends through the-bolster 6 and the crosshead 4 andhas a piston 11 secured to its upper end and tted in a knockout cylinder12 arranged upon the top of the crosshead 4. j

Liquid for advancing the plunger 10 to force a piece of work out of thedie '7 is supplied to the upper end of the cylinder 12 through a pipe13, and liquid for retracting the plunger 10 is delivered to the lowerend of the cylinder 12 through a pipe 14. y'

The upper stationary die 7 coacts with a lower movable male die l5 toform or draw a blank 16 into the shape determined by the conguration ofthe dies which, as shown, are adapted to form a substantiallyrectangular receptacle.

The lower die 15 is moved toward and from the upper die 'Z by a pressram 17 which is fitted in a cylinder 18 and provided upon its lower endwith a tail rod 19 having a piston 20 fixed thereon and tted in acylinder 21. The cylinders 18 and 2l are arranged within and carried bythe base 1 and are shown as being formed integral therewith.

During the drawing operation, the blank 16 is gripped between the lowerface of the die 7 and a lpressure ring 22 having formed therein acentral opening 23 which accommodates the lower die 15 and conformssubstantially to the periphery of the recess in the die 7.

The pressure ring 22 is moved toward and from the die 7 by fouridentical rams each of which is designated by the reference numeral 24and distinguished from the other rams 24 by the addition of the exponenta, b, c, or. r1 to its 'reference numeral. Each ram 24 is arranged in acylinder 25 and provided with a tail rod 2 6 having a piston 27 nxed toits lower end and fitted in a cylinder 28, and the cylinders, tail rodand piston associated with each ram have the same exponent added to thereference numerals thereoi.l as is added to the reference numeral of theram with which the same are associated. The cylinders 25 and 28 arearranged within and carried by the base 1 and have been shown as beingformed integral therewith.

The rams 24 are adapted to raise the pressure ring 22 and clamp themargin of the blank 16 between it and the lower face of the die 7, andthe force or pressure exerted by any one of the rams 24 may be varied byvarying the fluid pressure rin its cylinder 25 to thereby applydifferent pressures upon different parts of the margin of the blank.

In order to further vary the pressures upon different parts of themargin of the blanks and to apply a particular pressure upon anyparticular point thereof irrespective of the position of that pointrelative to the positions of the rains 24, the pressure ring may beprovided with an annular channel 29, a cover plate or top plate 30 whichcovers the channel and normally rests upon the side walls thereof, and aplurality of sylphons 31 which may be arranged in selected positions inthe channel 29 and supplied individually with pressure fluid to exertindividual pressures upon different points around the margin of theblank.

Each sylphon 31 has its side wall formedl of an expansible metal bellows32 and its ends closed by two heads 33 and 34 which are welded orotherwise rigidly secured in position to form fluid-tight joints withthe' bellows.

The lower head 33 has a projection 35 formed thereon and extendingupward into the bellows, and the upper end of this projection may bepositioned a short distance below the head 34 to limit the downwardmovement thereof.

The projection 35 is provided in the lower part thereof with a bore 36which is in open communication with the interior of the bellows 32, asby perforations 37, and is closed at its lower end by a plug 38 rigidlyfastened in the head 33.

The bellows 32 is expanded to raise the head 34 by liquid deliveredthrough a duct 39 which isv formed in the head 33 and communicates with"the bore 36, and the upward movement of the as readily be arrangedthereinpwith the heads 33 upward if so desired.

Liquid for operating the press is supplied by a positive displacementpump 42 which is driven at a constant speed by an electric motor 43 anddelivers liquid from a reservoir 44 into a supply pipe 45 having threebranches for the deliveryl of liquid to three separate control valves. Apump which may be employed is illustrated and described in Patent No.1,798,198 issued March 3l, 1931 to Walter Ferris and John P. Ferris.

One branch of the supply pipe 45 is connected to a port 46 in a controlvalve 47 which controls the delivery of liquid from the pump 42 to theknockout cylinder 12 and has the pipes 13 and 14 connected thereto incommunication, respectively, with two ports 48 and 49 arranged uponopposite sides of the port 48.

The flow of liquid through the valve 47 is con trolled by its plunger 50which is operated by a lever 5l. When the plunger 50 is in the positionshown in Fig. 4, the pump 42 may deliver liquid through the supply pipe45, the valve 47 and the pipe 14 to the lower end of the cylinder 12 andraise the piston 1l, and liquid expelled from the upper end of thecylinder 12 by the piston 11 is exhausted through the pipe 13 and thevalve 47 into a drain pipe 52 which is connected to both ends' of thevalve 47 and discharges into the reservoir 44. When the plunger 50 is inthe position shown in Fig. 6, the now of liquid in the pipes 13 and 14is reversed and the piston 11 will force the knockout plunger 10downward to eject the work from the die 7. y

A second branch of the supply pipe 45 is connected to a port 53 in areversing valve 54 which controls the delivery of liquid to the cylinder2l and has two ports 55 and 56 arranged upon opposite sides of the port53 and controlled by a plunger 57 which is operated by a lever 58. Theport 55 has connected thereto one end of a pipe 59 the other end ofwhich is connected to the upper end of the cylinder 21. The port 56 hasconnected thereto one end of a pipe 60 the other end of which isconnected to the lower end of the cylinder 2l.

When the plunger 57 is in the position shown in Fig. 4, liquid from thepump 42 may flow through the pipe 45, the valve 54 and the pipe 59 tothe upper end of the cylinder 21 and move the piston 126 20 downward,and the liquid expelled from the lower end of the cylinder 21 by thepiston 20 is exhausted through the pipe 60 and the valve 54 into thedrain pipe 52 which is connected to both ends of the casing of the valve54. When the plunger 57 is moved to the position shown in Flg. 7, the owof liquid in the pipes 59 and 60 isreversed and the piston 20 will bemoved upward.

When the piston 20 is moved upward, the ram 17 is moved upward and drawsliquid into the cylinder 18 from a surge tank 61 which is ordinarilyarranged upon the crosshead 4 as shown in Fig. 1. When the piston20moves downward, the ram 17 is moved downward and expels liquid from thecylinder 18 into the surge tank. 'I'he level of the liquid in the surgetank is limited by an overflow pipe 62 which discharges into thereservoir 44.

'I'he fiow of liquid between the cylinder 18 and the surge tank 61 iscontrolled by an automatic valve 63 which has aport 64 i'ormed thereinand connected by a pipe 65 to the cylinder 18, a port 66 arranged uponone side of the port 64 and connected by a pipe 67 to the surge tank,and a port 68 arranged upon the other side of the port 64 and connectedby a pipe 69 to the pipe 60.

The iiow of liquid through the valve 63 is controlled by its plungerwhich is operated by a piston 71 rigidly connected to one end thereofand fitted in acylinder 72 arranged upon one end of the valve casing.The cylinder 72 has its inner end connected to the pipe 59 by a pipe 73and its outer end connected to the pipe 60 by a pipe 74 which has acheck valve 75'and a resistance valve 76 connected in parallel therein.The check valve 75 permits liquid to be exhausted freely from the outerend of the cylinder 72 but forces liquid delivered thereto to passthrough the resistance Valve 76.

When the valve plunger 57 has been moved to the position shown in Fig. 7and liquid delivered to the lower end of tlf-e cylinder 21 has raisedthe piston 20 and the ram 17 until suiiicient resistance has beenencountered by the ram to cause the pressure in the pipe 60 to risesuiiciently to overcome the resistance of the valve 76, liquid willbreak through the valve 76, enter the cylinder 72 and move the piston 71and the valve plunger 70 to the position shown in Fig. 10, therebyclosing communication between the cylinder 18 and the surge tank 6l andopening communication between the cylinder 18 and the pipe 60 which atthis time is in direct communication with the pump 42 through the valve54 and the supply pipe 45. Liquid from the pump 42 then flows to thecylinder 18 and, acts upon the ram 17 and causes it to exert a highpressure upon the blank being'formed between the. dies 7 and 15.

The third branch of the supply pipe 45 is connected to a port 77 in ablank holder valve 78 through which liquid is delivered to the blankholder cylinders 25 and 28.

Liquid is delivered to and discharged from the upper ends oi thecylinders 28 through a'pipe 79 which is connected to the casing of thevalve 78 at the left of the port 77 and is provided with four branches79, 79, 79 and -79d which are connected, respectively, to the cylinders28, 28, 28 and 28d. In order that the pistons 27 may reciprocate`freely, the lowery end of each cylinder 28 is connected to the overflowpipe 62.

The four cylinders 25, 25, 25 and 25d are connected, respectively, byfour pipes 80, 80, 80c and 80d to four ports 81, 82, 83 and 84 which areformedin the casing of the valve 78 at the right of the port 77 andequally spaced from each other, and the port 81 is connected by a duct85 to a port 86 arranged at the right of the port 84.

The casing of the valve 78 also has a port 87 arranged therein at theright of the port 86 and a port 88 arranged between the ports 77 and 81.The overflow pipe 62 is connected'to the port 87 and to both ends of theValve casing, and the port 88 has a pipe 89 connected thereto. The pipe89 is connected to thefour pipes 80, 80, 80 and 8l)d through four chokes90, 90b, 90 and 90`l and four check valves 91, 91, 91 and 91d,respectively. The chokes 90 allow a very limited volume of liquid to owfrom the pipe 89 to each pipe 80 and the check valves 91 prevent the owof liquid in the opposite direction.

The ow of liquid through the valve 78 is controlled byits plunger 92which is operated by a lever 98 and provided with a piston 94, tocontrol communication between the pipe 79 and the port 77, and with anelongated piston 95 to control Acommunication between the port 77 andthe other ports. The elongated piston 95 is provided with transversepassageways 96, 97, 98, 99, 100 and 101 which, when the plunger 92 is inthe position shown in Fig. 4, register with the ports 81,

pressure which the rams 24, 24, 24 and 24 may 82, 83, 84, 86 and 87respectively. The transverse passageways all communicate with each otherthrough a longitudinal passageway 102 which is formed within theelongated piston 95 and closed at each of its ends. v 80 When theplunger 92 is in the position shown in Fig. 4, liquid from the supplypipe 45 may ilow through the valve 78 and move the pistons `27 and therams 24 downward, and the liquid expelled from the cylinders 25 by therams 24 may ow through the pipes 80 and the valve 78 to the overow pipe62.

When the plunger 92 is in the position shown in Fig. 8, the port 81 isopen to the port 77 and communication is established between the port 77and the ports 82, 83, and 84 through the transverse passageways 96, 97and 98, the longitudinal passageway 102, the transverse passageway 99,the duct and the port 8l, thereby permitting liquid to ilow from thesupply pipe 45 through the valve 78 and the pipes 80 to the cylinders 25and raise the rams 24 to grip the blank 16 between the pressure ring 22and the die 7. The

exert =upon the blank is limited, respectively, by adjustable resistanceValves 103, 103, 103, and 103d connected between the pipes 80a, 80, 80and 80, respectively, and the overflow pipe 62. When the valve 78 hasits plunger 92 in the position shown in Fig. 9, the ports 8l, 82, 83, 84105 and 86 are closed by the piston 95 to prevent the escape of liquidlfrom the cylinders 25 through the valve 78, and theport 88 is open tothe port .77 to permit pressure to extend from the supply pipe 45through the pipe 89, the Chores so and 110 check valves 91 into thecylinders 25 to maintain pressure therein. The pressure in each cylinder25 is determined by itsresistance valve 103 which may be adjustedto varythat pressure, and a variation in pressure in one cylinder 25 isprevented from affecting the pressure in any other cylinder 25 by thechokes 90 and the check valves 91. Consequently, the pressure in eachcylinder 25 is independent of the pressure in any other cylinder 25.

Liquid for operating the sylphons 3l is supplied thereto through amanifold pipe 104 which is connected to each cylinder 25 through ashutoi valve 105 and a duct 106 formed in the ram 24 and extendingtherethrough.

If all of the shutoi valves 105 remained open, pressure in all of thecylinders 25 would equalize through rthe pipe 104 and the maximumpressure obtainable therein would be determined by the resistance valve103A which was adjusted to open at a lower pressure than the otherresistance valves 103. In order to permit diierent pressures to becreated in the several cylinders 25, all of the shutoff valves 105 areclosed except the one which isv connected to the cylinder 25 whoseresistance valve 103 is adjusted to open at a pressure higher than thepressure required to open the other resistance valves 103. Consequently,the pipe 104 may have a pressure created therein which is substantiallyequal to the highest pressure created in any of the cylinders 25.

Each sylphon 31 is connected to the pipe 104 by a pipe 107 (Fig. 5)which has a choke 108 and a check valve 109 connected in paralleltherein. The choke 108 permits liquid to flow from the pipe V104 to thesylphon 31 at a limited rate, and the check valve 109 permits liquid toow freely from the sylphon 31 to the pipe 104 but prevents it fromiiowing in the opposi di-rection except-through the choke 108. 15

'adjusted to open at the maximum pressure desired in the sylphon towhich it is connected and, as the chokes 108 limit the flow of liquid toeach sylphon, a different pressure may be obtained in each sylphon andthe pressure in any sylphon may be regulated or varied without aiectingthe pressure in any other sylphon.

The combined capacity of all of the chokes 108 is less than the capacityof one choke 90 in order that each choke 90 may supply to the cylinder25 to which it is connected a volume of liquid sufficient to maintaintherein the maximum pressure determined by the adjustment of theresistance valve 103- connected thereto and to also maintain the desiredmaximum pressures in the several sylphons.A

. Assuming that the pump 42 is running and that the several rams,pistons and valve plungers are in the positions shown in Fig. 4, thepump will have created a predetermined pressure in the upper ends of thecylinders 21 and 28 and in the lower end of the cylinder 12 andautomatically reduced its stroke until it is delivering just suilicientliquid to compensate for leakage and maintain that pressure constant. asfully described in Patent No. 1,798,198 referred to above.

I f the lever 93 is then operated to move the plunger 92 of the valve 78to the position shown `in Fig. 8, liquid from the pump 42 will owthrough the supply pipe 45, the valve 78 and the pipes 80 to the lowerends of the 'cylinders and raise the rams 24' which will raise thepressure ring 22 to move the blank l6 into contact with the upper die 7.The plunger 92 is ordinarily retained in this position until suiiicientpressure has been created in the several cylinders 25 to open one of theresistance valves 103, thereby causing the margin of the blank 16 to begripped between the pressure ring 22 and the upper die 7.

At the same time, liquid ows through the shutoff valve 105 which is openand then through the pipes 104 and 107 and the chokes 108 to thesylphons 31 and creates pressure therein to cause the sylphons to exertpressure upon the margin v oi' the blank at dierent points thereon.

The lever 93 is then operated to move the plunger 92 of the valve 78 tothe position shown in Fig. 9 in which position it blocks the ports 81,82, 83 and 84 and prevents the escape of liquid from the cylinders 25but leaves the port 88 open to the port 77 to permit liquid to now fromthe supply pipe into the pipe 89 and through the chokes 90 and checkvalves 91 into the several cylinders 25 to maintain or create in eachcylinder 25 a pressure sufficient to open theresistance valve 103connected thereto, thereby maintaining a particular pressure in eachcylinder.

At the same time, liquid flows from one of the cylinders 25 through theduct 106, the open shutoff valve 105, the pipes 104 and 107 of thechokes 108 to the several sylphons 31 and creates or maintains in each apredetermined pressure in accordance with the adjustment of theresistance valve 110 connected thereto.

The lever 58 is then operated to move the plunger 57 of the valve 54 tothe position shown in Fig. 7 to open the pipe 59 to the drainpipe 52 andopen the pipe 60 to the pipe 45, thereby permitting liquid from the pump42 to flow through the pipe 60 to the lower end of the cylinder 21 andraise the piston 20 and the ram 17, the liquid in the upper end of thecylinder 21 being exhausted through thepipe 59 and the valve 54 into thedrain pipe 52 and the ram 17 drawing liquid into its cylinder 18 fromthe tank 61 through the pipe 65, the valve 63 and the pipe 67 aspreviously described.

When the plunger -57 of the valve 54 is shifted to open the pipe 60 tothe pipe 45, the pressure in the pipes 45 and 89 drops momentarily butthe check valves 91 and 109.prevent a materialdrop in the pressures inthe cylinders 25 and in the sylphons 31.

Engagement of the die' 15 with the blank 16 retards the upward movementof the piston 20 and causes the pressure in pipes 60 and 69 to riseuntil liquid breaks through the resistance valve 76 and operates thepiston 71 to.move the plunger of the valve 63 to the position shown inFig. 10, thereby closing the pipe 65 to the pipe 67 and opening it tothe pipe 60 through the pipe 69.

Liquid from the pump 42 now flows through the valve 63 and the pipe 65to the cylinder 18 and continues to flow through the pipe 60 to thecylinder 21, thus acting upon the combined eifective areas of the ram 17and the piston 20 and moving the ram upwardly to force the die 15 intothe die 7 and draw or form an article from the `blank 16. At the sametime, a limited volume of liquid is ilowing through the chokes 90 tomaintain or create the desired pressures in the cylinders 28 and thesylphons 31.

The press is thus operated by liquid supplied from a single pump,pressure is maintained in its blank-holding cylinders and sylphons whilethe press ram is being operated, and the pressure in each blank-holdingcylinder or sylphon is substantially independent of the pressure in anyother blank-holding cylinder or sylphon.

After the blank has been formed, the levers 58 and 93 are operated toreturn the valve plungers 57 and 94 into the positions shown in Fig. 4.Liquid may now flow through the valve 54 to the upper end of thecylinder 21 and through the valve 78 to the upper ends of the cylinders28 and retract the rams 17 and 24 to their initial positions, aspreviously described.l l

The lever 51 is then operated to move the plunger 50 of the valve 47 tothe position shown in Fig. 6, thereby permitting liquid from the pump 42to flow into the upper end of the cyl- -inder 12 to advance the piston11 and cause the plunger 10 to eject the finished article from the die7. The lever 51 is then operated to return the plunger 50 to theposition shown in Fig. 4 and thereby permit liquid t'o ilow to the lowerend of the cylinder 12 and retract the piston 11 to its initialposition.

The invention herein set forth is susceptible of various modificationsand adaptations without dleperting from the scope thereof as hereafter14o c 'Ihe invention is hereby claimed as follows: 1. The combination,with a source of pressure fluid, of a holding cylinder, a power cylinderhaving a plunger fitted therein, means for deliver- 14,5 ing iiuidfreely from said source to each of said cylinders selectively tocreate'a predetermined pressure in said holding cylinder and to operatesaid plunger, and means connected between said source and said holdingcylinder to enable said 15 source to maintain said predeterminedpressure substantially constant while delivering fluid freely tosaidpower cylinder.

2. The combination, with a pump, of two cylinders, means for deliveringfluid freely from said source to the first of said cylinders and then tothe second cylinder to create pressure therein, and additional meansconnected between said pump and the rst of said cylinders to enable saidpump to deliver a limited volume ofuid to that cylinder while deliveringfluid freely to the second cylinder.

3. The combination, with a holding cylinder and a power cylinder, of apump 'for supplying iiuid` to said cylinders, means for delivering fluidfrom said pump to said power cylinder freely, and means forsimultaneously delivering fluid from said pump to said holding cylinderand including a choke for limiting the flow of fluid thereto and a checkvalve for preventing the free escape of fluid therefrom.

4. The combination, with a power cylinder and a holding cylinder, of apump for supplying fluid to said cylinders, iiuid .channels forconnecting said holding cylinder to said pump, valve means for directinguid from said pump through said channels to said holding cylinder tocreate pressure therein and operable to block said channels between saidholding cylinder and said pump, means for directing fluid from said pumpto said power cylinder, and a choke connected'between said cylinders toenable said pump to deliver a limited volume of Huid to said holdingcylinder while delivering iiuid to said power cylinder.

5. {Ihe combination, with a source of pressure fluid, of a plurality ofholding cylinders, a power cylinder having a plunger fitted therein,means for delivering iiuid freely from said source to each of saidcylinders to create pressure in said holding cylinders and to operatesaid plunger, and means connected between said source and said holdingcylinders to enable said source to maintain pressure in said holdingcylinders while delivering fluid freely to said power cylinder, andmeans for regulating the pressure in one holding cylinder independentlyof the pressure in another holding cylinder.

6. The combination, with a plurality of holding cylinders and a powercylinder, of a pump for supplying uid to said cylinders, means fordelivering fluid from said pump to said power cylinder freely, means forsimultaneously delivering fluid from said pump to said holding cylindersand including a choke for limiting the ow of uid to -each holdingcylinder and a check valve for preventing the free escape of fluidtherefrom, and means for regulating the pressure in one holding cylinderindependently of the pressure in another holding cylinder.

' 7. The combination, with a power cylinder and a plurality of holdingcylinders, of a pump for supplying fluid to said cylinders, fluidchannels for connecting said holding cylinders to said pump, valve meansfor directing fluid from said pump through said channels to said holdingcylinders to create lpressure therein and operable to block saidchannels between said holding cylinders and said pump, means fordirecting fluid from said pump to said power cylinder, and a chokeconnected between said power cylinder and each of said holding cylindersto enable said pump to deliver limited volumes of iiuid to said yholding cylinders while delivering fluid to said power cylinder, andmeans for regulating the pressure in one holding cylinder independentlyof the pressure in another holding cylinder.

8. A draw press, comprising a frame having a stationary die and amovable die for operatpressure units carried by said pressure ring toexert pressure upon different parts of the blank, means for deliveringiiuid to said units to operate the same, and means for varying thepressure exerted by each unit upon the blank.

9. A draw press, comprising a frame having a stationary die and amovable die for operating upon a blank, a cylinder arranged in saidframe and having a ram fitted therein for advancing said movable dietoward said stationary die and retracting lit therefrom, a blank holderhaving a pressure ring to grip the blank between it and said stationarydie and means for advancing said pressure ring Atoward said stationarydie and retracting it therefrom, a pump, means for delivering fluid fromsaid pump to said cylinder to operate said ram, a plurality of fluidactuated pressure units connected in parallel and carried by saidpressure ring to exert pressure upon different parts of the blank, meansfor delivering fluid to said units to operate the same includ- 110 ing achoke and a check valve connected to each unit in parallel with eachother, and means for varying the pressure exerted by each unit upon theblank. Y

10. A draw press, comprising a frame having a stationary die and amovable die for operating upon a blank, a cylinder arranged in saidframe and having a ram fitted therein for advancing said movable dietoward said `stationary die and retracting it therefrom, a blank holderhaving a pressure ring to grip the blank between it and said stationarydie and a plurality of fluid motors for advancing said pressure ringtoward said stationary die and retracting it therefrom, a pump,

means for delivering iiuid from said pump to said motors to operate thesame and create pressure therein, means for delivering iuid to said ramcylinder to operate said ram, a plurality of pressure units carried bysaid pressure ring to exert pressure upon different parts of the blank,and means for connecting said pressure units in circuit with saidmotors. u

11. A draw press, comprising a frame having a stationary die and amovable die for operating upon a blank, a cylinder arranged in saidframe and having a ram tted therein for advancing said movable dietoward said stationary die and retracting it therefrom, a blank holderhaving a pressure ring to grip the blank between it and said stationarydie and a plurality of uid motors for'advancing said pressure ringtoward said stationary die and retracting it therefrom, a pump, meansfor delivering fluid from said pump to said motors to operate the sameand create pressure therein, means for limiting the pressure of saidmotors for the flow of uid therebetween, and a shutoif valve connectedbetween said pressure units and each motor.

12. A draw press, comprising a frame having a stationary die and amovable die foroperating upon a blank, a cylinder arranged in said frameand having a ram iltted therein for advancing said movable die towardsaid stationary die and retracting it therefrom, a blank holder having apressure ring to grip the blank between it and said stationary die and aplurality of fluid motors for advancing said pressure ring toward saidstationary die and reti-acting it therefrom, a pump, means fordelivering fluid from said pump to said motors to operate the same andcreate pressure therein, means for delivering iluid to said ram cylinderto operate said ram, a plurality of pressure units carried by saidpressure ring to exert pressure upon different parts of the blank, meansfor connecting said pressure umts in circuit with said motors, and meansfor limiting the pressure in one pressure unit independently of thepressure in another pressure unit.

13. A draw press, comprising a frame having a stationary die and amovable die for operating upon a blank, a cylinder arranged in saidframe and having a ram iitted therein for advancing said movable dietoward said stationary die and retracting it therefrom, a blank'holderhaving a pressure ring to grip the blank between it and said stationarydie and a plurality of uid motors for advancing said pressure ringtoward said stationary die and retracting it therefrom, a pump, meansfor delivering fluid from said pump to said motors to operate the sameand create 'pressure therein, means for limiting the pressure in eachmotor, means for delivering fluid to said ram cylinder to operate saidram, a plurality of pressure units carried b'y said pressure ring toexert pressure upon diilerent parts of the blank, means for connectingsaid pressure units to each of said motors for the flow of fluidtherebetween, a shutoff valve connected between said pressure units andeach motor, and means for limiting the pressure in one pressure unitindependently of the pressure in another pressure unit.

14. A draw press, comprising a frame having a stationary die and amovable die for operating upon a blank, a cylinder arranged in saidframe and having a ram fitted therein for advancing said movable dietoward said stationary die and retraoting it-therefrom, a blank holderhaving a pressure ring to grip the blank between it and said stationarydie and a plurality of uid motors for advancing said pressure ringtoward said stationary die. and retracting it therefrom, a pump, meansfor delivering fluid from said pump to said motors to operate the sameand create pressure therein, means for diverting said delivery of uidfrom said motors to said ram cylinder to operate said ram, a chokeconnected between each of said motors and said ram cylinder for enablingsaid pump to deliver a limited volume of fluid to each motor to maintainpressure therein while delivering uid freely to said ram cylinder tooperate said ram, and a check valve connected in series with said chokefor preventing the ilow of fluid therethrough in the opposite direction.

15. A draw press, comprising a frame having a stationary die and amovable die for operating upon a blank, a cylinder arranged in saidframe and having a ram fitted therein for advancing-said movable dietoward said stationary die and retracting it therefrom, ablank holderhaving a pressure ring to grip the blank between it and said stationarydie and a plurality of fluid motors for advancing said pressure ringtoward said stationary die and retracting it therefrom, a pump, means-for delivering fluid from said-pump to said motors to operate the sameand create pressure therein, means for diverting said delivery of fluidfrom said motors to said ram cylinder to operate said ram, a chokeconnected between each of said motors and said ram cylinder for enablingsaid pump to deliver a limited volume of fluid to each motor to maintainpressure therein while delivering fluid freely to said ram cylinder tooperate said ram, a check valve connected in series with said choke forpreventing the flow of fluid therethrough in the opposite direction, andmeans for regulating' the pressure in one motor independently .of thepressure in another motor. y 18. A draw press, comprising a frame havinga stationary die and a movable die for operating upon a blank, acylinder arranged in said frame and having a ram fitted therein foradvancing said movable die toward said stationary die and retracting ittherefrom, a blank holder having a pressure ring to grip the blankbetween it and. said stationary die and a plurality of iluid motors foradvancing said pressure ring toward said stationary die and retractingit therefrom, a pump, means for delivering uid from said pump to saidmotors to operate the same and create pressure therein, means fordiverting said delivery of fluid from said motors to said ram cylinderto operate said ram, a choke connected between each of said motors andsaid ram cylinder for enabling said pump to deliver alimited volume offluid to each motor to maintain pressure therein while delivering fluidfreely to said ram cylinder to operate said ram, a check valve connectedin series with said choke for preventing the flow of iluid therethroughin the opposite direction, a plurality of pressure units carried by saidblank holder to exert pressure upon the blank, and means for deliveringfluid to said pressure units to operate the same.

17. A draw press, comprising a frame, having a stationary die and amovable die for operating upon a blank, a cylinder arranged in saidframe and having aram fitted therein for advancing said movable dietoward said stationary die and retracting it therefrom, a blank holderhaving a pressure ring to grip the blank between it and said stationarydie and a plurality of fluid motors for advancing said pressure ringtoward said stationary' die and retractlng it therefrom, a pump, meansfor delivering uid from said pump to said motors to operate the same andcreate pressure therein, means for diverting said delivery of fluid fromsaid motors to said ram cylinder to operate vsaid ram, a choke connectedbetween each of said motors and said ram cylinder for enabling said pumpto deliver a limited volume of fluid to each motor to maintain pressuretherein while delivering fluid freely to said ram cylinder to operatesaid ram, a check valve connected in series with said choke forpreventing the flow of fluid therethrough in the opposite direction,means for regulating the pressure in one motor independently of thepressure in'another motor, a plurality of pressure units carried by saidblank holder to exert pressure upon the blank, and means for deliveringuid to said pres- .sure units to operate 'the same.

Lerares f said movable die toward said stationary die and retractlng ittherefrom, a blank holder having a pressure ring tc grip the blankbetween it and said stationary die and a plurality of fluid motors foradvancing said pressure ring toward said stationary die and reti-actingit therefrom, a pump, means for delivering fluid from said pump to saidmotors to operate the same and create pressure therein, means fordiverting said delivery of duid from said motors to said ram cylinder tooperate said ram, a choke connected between each of said motors and saidram cylinder for enabling said pump to deliver a limited volume of fluidto each motor to maintain pressure therein while delivering fluid freelyto said ram cylinder to operate said ram, a check valve connected inseries with said choke for preventing the flow o fluid therethrough inthe opposite direction, a plurality of pressure units carried by saidblank holder to exert pressure upon the blank, means ior dellveringsuidto said pressure units to operate the same, and means for limiting thepressure in one pressure unit independently of the pressure in anotherpressure unit. Y

19. A draw press, comprising a frame having a stationary die and amovable die for operating upon a blank, a cylinder arranged in saidframe and having a ram tted therein for advancing said movable dietoward said stationary die and retracting it therefrom, a blank holderhaving a' pressure ring to grip the blank between it and said stationarydie and a plurality of duid motors for advancing said pressure ringtoward said stationary die and retraoting it therefrom, a pump, meansfor delivering duid from said pump to said motors to operate the sameand create pressurev therein, means for diverting said delivery of uidfrom said motors to said ram cylinder to operate said ram, a chokeconnected between each of said motors and'said ram cylinder for enablingsaid pump to deliver a. limited volume of liuid to each motor tomaintain pressure therein while delivering uid freelyto said ramcylinder to operate said ram, a check valve connected in series withsaid choke for preventing the flow of fluid therethrough in the oppositedirection, means for regulating the pressure in one motor independentlyof the pressure in another motor, a plurality of pressure units carriedby said blank holder to exert pressure upon the blank, means fordelivering uid to said pressure units to operate the same, and means forlimiting the pressure in one pressure unit independently of the pressurein another pressure unit 20. A draw press, comprising a frame having astationary die and a movable die for operating upon a blank, a cylinderarranged in saidframe and having a ram fitted therein for advancing saidmovable die `toward said stationary die and retracting it therefrom, ablank holder having a pressure ring to grip the blank between it andsaid stationary die and a plurality of fluid motors for advancing saidpressure ring toward said stationary die and retracting it therefrom, apump, means for delivering fluid from said pump to said motors tooperate the same and create pressure therein, means for diverting saiddelivery of fluid from said motors to said ram cylinder to operate saidram, a choke connected between each of said motors and said ram cylinderfor enabling said pump to deliver a limited volume of fluid to eachmotor to maintain pressure therein while delivering :duid freely to saidram cylinder to operate said ram, a check valve connected in series withsaid choke for preventing the ow .of uid therethrough in the oppositedirection,

means for regulating the pressure in one motor independently of thepressure in another motor,

a plurality of pressure units connected in parallel with each other andcarried by said pressure ring to exert pressure upon different parts oflthe blank, a relief valve connected to each pressure unit for limitingthe pressure therein, and means for connecting said pressure units toeach of said motors for the flow of fluid therebetween and in-h cludinga shutoff valve Aconnected 4between each motor and said pressure unitsand a choke and a check valve connected to each pressure unit inparallel with each other.

WALTER FERRIS.

